In order to prevent from being brought out of the business premises illegally, merchandises in the shopping malls, supermarkets and other open shelves are often equipped with merchandise anti-theft device. These anti-theft devices are generally connected and carried with merchandises in different means. When merchandises are stolen and pass the antenna door of the security system, it will trigger alarms. This kind of anti-theft system has the feature of real-time response, but it can give alarms only for the theft itself, cannot give alarms accurately for the stolen merchandises and the time of theft, nor have recording function. Thus, with the increasing respect of public interest, the existing anti-theft system will easily lead to disputes over rights.
For the door access and gateway system with the data checking and data recording functions, the real-time performance is of important significance due to the existence of data communication and storage, and it is also an important factor influencing its performance and scope of applications.